I did the journey both ways in Spring this year.
On the way back from Türkiye, the attendant did look a bit surprised when I asked him to let me off at Dimitrovgrad. I'd bought a ticket to Sofia as I was playing with the idea of going past Dimitrovgrad then returning in order to avoid the long wait at Dimitrovgrad in the middle of the night. But the sleep deprivation was such that I felt I would make a mistake if I tried to do that. So I got off at Dimitrovgrad. Bizarrely the ticket office was staffed by 2 people there through the night. But none of the vending machines took credit cards so - with, I admit, a little trepidation, I ventured out into the night. It's a nice town in the middle of the night, I wondered through a long pedestrian shopping square in a classic style with fountains etc, wondered around a park, etc. One of the highlights of the trip.
The other connections were all fine.